Treatment of ores and metallurgical products



Oct 15, 1929.

H. G. HEINE TREATMENT OF ORES AND METALLURGICAL PRODUCTS Filed A i-n 23,1927 2 Sheets-Sheet 1 Fig. 1

Oct. 15, 1929. H. s. HEINE 1,731,393

TREATMENT OF ORES AND METALLURGICAL PRODUCTS.

Filed April 23, 1-927 z sheets-sheet 2 Mvenforr:

.the section of the kiln Patented 0a. is, 1929 UNITED STATES PATENTOFFICE GERMANY, ASSIGNOR T0 FRIED. KRUPP OF MAG-DEBURG-BUCKAU, GERMANY'I'REATMEN 0F ORES AND METALLURGICAL PRODUCTS Application filed April23, 1927, Serial No. 188,053, and in Germany April 28, 1926.

My invention relates to a process of volatilization of metal in the formof metal fume or in the form of oxidic compounds or compounds containingchlorin or sulphur, or admixtures of such in reverberatory furnaces i.e., rotary kilns. In processes of this kind it is of importance that thetemperature in the furnace shall rise uniformly from the charging end upto the main reaction zone and shall be maintained in this zone as longas possible at the same degree for the purpose of attaining as completea volatilization as possible and to avoid an agglomeration or fusion inthe main zone of reaction.

The object of my invention is to maintain an even maximum temperatureduring a period of greater length. I propose to reduce (temporarily orpermanently by steps) the transverse section of the furnace, forinstance of a rotary kiln in the direction of the travel of thematerial.

The accompanying drawings show diagrammatically apparatus for carryingout the process.

Fig. l is a section of a furnace containing one step built of bricks;

Fig. 2 is a section of a furnace containing several brick steps ofgradually increasing height;

Fig. 3 shows a different arrangement of several steps arranged for aprocess which is carried out in two stages, for instance a calcinationstage followed by a volatilization stage; and

Fig. 4 shows a furnace containing a step built up by fusing to the wallof the furnace a ring of the material to be treated.

In the drawings a is a rotary kiln of the usual type, Z), 6 b b b b and6 represent steps constructed of brick or similar material, while 6represents a step built up by fusing to the wall of the furnace a ringof the material to be treated, and 0 represents the material undergoingtreatment. l5

As required one may provide one or more steps and it may be of advantageto enlarge after one, or several steps. The steps can also be formedduring the treatment by burning in the material which forms ring-shapeddeposits on the lining owing to the rotary movement of the kiln. In thisway the position of the steps in the furnace may be changed ad libitumby varying the point to which the heating flame is directed for instanceaccording to the always varyino composition of the material to be treateBy the use of such steps by means of Which the section of the kiln isreduced, the material travelling through the furnace'is retarded in sucha way, that in front of such a step a layer of gradually increased depthis forn'ied in the kiln. As a result the heating of the material infront of the step by the heating gases is lessened because a greatersurface of the charge is in contact with the cooler lining, while thesurface of the charge exposed to the heating gas, relative to the entiremass of the charge, is considerably reduced. By reducing the surface aslowing of the chemical exothermic reaction is attained. In this way itis possible by choosing the height and number of the steps to form zonesof even temperature inside of the kiln.

In the application of this invention to the volatilization of zinc, thezinc-bearing material, mixed with reducing material, is charged at theupper end of the furnace, and in consequence of the turning and theinclination of the furnace it slowly progresses along the furnace. Theeffect of a heating flame or of the combustion of the reducing materialslowly heats the material up to the point where reduction andvolatilization begin.

In consequence of the action of the heating flame the material is eithergradually so overheated that it melts, or, if care is taken to raise thetemperature so slowly that no melting takes place, the zinc only beginsto volatilize shortly before it reaches the hottest part of the flameand the material leaves the furnace before a complete dezincing has beenattained.

According to the present invention one or more steps are built up nearthe discharge end of the furnace so that the material piles up to theheight of the steps. This piling up causes a change in the relation ofthe volume to the exposed surface of the layer of material. The coolingeffect of the endothermic reaction taking place in the interior of thelayer of material is therefore no longer ex ceeded by the heating effectat the surface and.

by proper choice of the position and height of the steps these efiectscan be exactly compensated. .In this way it is possible to maintain azone of relatively high, but uniform, tem-' perature in the furnace, andto carry out the deslred volatilization to an essentially completedegree, without fear of overheating the material with'a resultingmelting or sintering. -Various changes and modifications may be made inthe design and the structural details of the rota furnace usedconsistent with the nature 0 the material to be treated, and

- in'the respective steps for obtaining the best 'ble results by myimproved process without substantially departing from the spirit ofthisinvention. v

Having now particularly described and ascertained the nature of my saidinvention and-in what manner the same is to be performed, I declare thatwhat I claim is:

1. Aprocess; for recovering volatilizable metals from ores,metallurgical products and residues, by subjecting said materials to theaction of heat in a kiln which comprises forming zones of uniformtemperature of reaction within the kiln by locally reducing thetransverse section of the kiln so that the height of the layerofmaterial is varied.

2.. A process as claimed in claim 1 wherein the local reductionoi thetransverse section I of thekiln is eflected by means of steps.

'3. A process as claimed inclaiml wherein the local reduction ofthetransverse section of the kiln is efiected by means of a pluralitygliteps arranged at various laces within the 1m this 11:

The forei ing specification signed at Ber- .day of fi'il, 1927'. HANS GHARD HEINE.

